Heat transfer



July 28, 1942. s. E. BlcKLE 22912146 HEAT. TRANSFER Filed March 4, 1939 2 SheetS-She'et l l L I l 60 l l 45 .Il 7d ff g 70 E y l "ll "1| :l |"l H g UP ii i |I 55 f4 I 'IMK` Il 1 (55 (62 liif@ ik A "El -'l-Z- 44) INVENTOR (54 I .Sal/(ZAg Biel/ Y I 0^ 'f ATTORN Y S. E. BICKLE July Z8, 1942.

2 Sheets-Sheet 2 HEAT TRANSFER Filed March 4, 1939 INVENTOR Patented July 28, 1942 HEAT TRANSFER Samuel E. Bickle, Highland Park, Mich., assignor to Borg-Warner Corporation, Chicago, Ill., a corporation of Illinois Application March 4, 1939, Serial No. 259,752

(Cl. (i2-126) 4 Claims.

This invention relates to the art of refrigeration and has particular reference to a new and improved form of heat absorbing or evaporator element which, as illustrated, is particularly designed for use in the provision compartment of household refrigerators, said evaporator being provided with a wall adapted to receive liquid holding trays and with an extensive heat absorbing surface over which air in the provision compartment of such refrigerator is adapted to circulate.

Heretofore, evaporators for domestic refrigerators have been designed so that the internal walls thereof dene a part of a freezer compartment and so that the external walls thereof provide a heat absorbing surface and shield the contents of the freezing compartment from circulating air within the provision compartment.

It is a primary object of this invention to provide a new and improved form of evaporator which may be constructed in two more or less independent parts, one part of which is primarily adapted and designed for ice freezing and the other part of which is primarily adapted and designed for air cooling.

Another object of the invention is to provide a new and improved form of evaporator with a great amount of heat absorbing surface over which the air in the provision compartment may circulate.

Another object of' the invention is to provide an evaporator with heat absorbing surfaces internally and externally thereof and over which the air in the provision compartment is adapted t circulate.

Another object of the invention is t0 provide a new and improved form of evaporator which may be adapted for producing refrigeration at two different temperatures simultaneously.

Other objects and advantages of the invention will be apparent from a consideration of the following specification taken in conjunction with the accompanying drawings of which there are two (2) sheets and wherein:

Fig. 1 is an elevational View partially broken away and partially in section and illustrating a refrigerator of the household type embodying a refrigerating system including an evaporator of the type herein contemplated;

Fig. 2 is an enlarged front elevational view of an evaporator or heat absorbing element embodying this invention;

Fig. 3 is a plan View of the evaporator illustrated in Fig. 2; and

Fig. 4 is a horizontal sectional view through the evaporator taken in the plane along the line 4 4 of Fig. 2 looking in the direction of the arrows.

In Fig. l there is illustrated a household refrigerator having a heat insulated provision compartment I0, an apparatus compartment I2 and a refrigerating system including a condensing unit assembly arranged in the apparatus compartment l2, and an evaporator arranged in the provision compartment I0 and operatively connected to the condensing unit assembly. The

ycondensing unit assembly may comprise, as illustrated, conventional elements of refrigerating systems, such as, a motor I4, a compressor I6 adapted to be driven by the motor, a condenser I8, a refrigerant expansion control comprising a high side float 20 and an electric cord 22 adapted to be connected to a suitable electric receptacle so as to supply current to the motor I4 for operating the same. The supply of current to the motor I4 may be under the control of a thermostatic and manually adjustable switch and cold control 24 which includes a thermostatic element 26 thermally associated with a part of the evaporator, said switch 24 being adapted normally to open and close the motor circuit in accordance with predetermined temperature variations of the evaporator, thereby effecting the operation of the refrigerating system in such a way as to maintain the temperature of the provision compartment within certain fairly definite limits.

The evaporator 25 is connected to the condensing unit assembly by a liquid refrigerant supply line 3i) which may consist of a capillary tube and so as to .be supplied with liquid refrigerant under the control of the refrigerant expansion control 2G, and the upper part of the evaporator is connected to the intake side of the compressor by return suction line 32 which, as illustrated, may be arranged in heat exchange relationship with the liquid refrigerant supply line Sil.

In general, the evaporator 28 consists of a plurality of sections or parts, namely, the freezing or low temperature section, indicated generally nents, both of which components will vaporize in the evaporator at the temperature level at which the system operates, said liquid having a different boiling point than that of its components. Examples of refrigerant mediums having a mixture of two or more components are:

Sulphur dioxide (SO2) and dichlorodifluoromethane (CClzFz) commonly known as F-12; and

Sulphur dioxide (SO2) uoromethane (CClsF) F-ll.

For further examples of suitable refrigerant consisting of two or more components, reference may be had to the application of Earl F. Hubacker, Ser. No. 179,249, led December 11, 1937, for Method of and apparatus for heat transfer wherein such refrigerants are broadly disclosed and claimed.

It will be observed that refrigerant passes through the sections 34 and 3B in series and that there are no restrictions between the two evaporator sections so that evaporation of refrigerant must take place at substantially the same suction pressure. When using the foregoing refrigerant consisting of two or more components, part of the refrigerant mixture will be evaporated in the freezing section 34 and the liquid refrigerant not vaporized in the freezing section 34, as well as the vaporous refrigerant generated in 34, will be delivered to the air cooling section 36. While the percentage composition of each of the components or constituents of the mixture will depend upon the temperature eifect desired in each section of the evaporator, we may assume for purposes of illustration the use of a refrigerant mixture comprising a five to ten percent solution, by weight, of F-12 to SO2. With a refrigerant such as this the absorption of heat may take place in the freezing section of the evaporator at a temperature level of from to and the absorption of heat in the air cooling section of the evaporator may take place at a temperature level of from 25 to 30 F. In the freezing section 34 of the evaporator, due to the fact that the liquid contains five to ten percent of F-l2 which is more volatile than SO2, the absorption of heat by the refrigerant will effect the vaporization of all or substantially all of the F-lZ as a result of which the liquid refrigerant fed to the air cooling section of the evaporator will consist of pure or substantially pure liquid SO2. Due to the percentage of F-l2 which is present in the liquid refrigerant in the freezing section 34, the temperature at which vaporization of the liquid will take place will be materially lower than the temperature at which vaporization of pure SO2 will take place as a result of which heat absorption will take place in the freezing section 34 at a materially lower temperature than that at which the absorption of heat takes place in the air cooling section 36.

While I have illustrated one method by which two temperature evaporation may be effected, I do not intend to limit myself to the production of two temperature evaporation in accordance with the method just disclosed as other methods of effecting two temperature evaporation heretofore known in the art may be used in connection with my evaporator design so that the section 34 will operate at a lower temperature level than the section 36. For a better understanding of the method of producing two temperature refrigeration by the use of a binary refrigerant, reference may be had to French Patent No.

and trichloromonocommonly known as 815,712, issued July 2l, 1937, to Borg-Warner Corporation.

Due to the fact that both the inside and outside surfaces of the Walls of the air cooling section of the evaporator are exposed to the circulating air within the provision compartment, it will be apparent that I have provided a greatly increased cooling area at practically no additional cost, that the absorption of heat is more efficiently carried on by the air cooling section of the evaporator due to the fact that the air passes in heat exchange relationship with both sides thereof, also, it will be observed that due to the particular arrangement of the walls of the air cooling evaporator that the air cooling surface extends not only on the sides of the evaporator but also at the back thereof. For the amount of space occupied by this evaporator, there is considerably more area of heat absorbing surface than there is in conventional evaporators. Also, there is greatly increased cooling surface and, also, due to the fact that a separate evaporator is provided for freezing ice, the temperature at which the air cooling evaporator will be operated may be considerably higher than that heretofore utilized and yet obtain a lower box temperature as well as a relatively higher humidity of the air within the box. This construction enables the use of fins to be dispensed with. Of course, the walls of the air cooling section of the evaporator should be spaced from both the side. and back walls of the provision compartment so as to expedite the circulation of air. over both the inside and outside surfaces of the walls of the evaporator.

While the invention has been described with some detail, it is to be understood that the description is for the purpose of illustration only and is not definitive of the limits of the inventive idea. The right is reserved to make such changes in the details of construction and arrangement of parts as will fall Within the purview of the attached claims.

I claim:

1. Refrigerating apparatus comprising a provision compartment having an evaporator element arranged therein, said evaporator element comprising continuous vertical heat absorbing walls provided by sheet metal arranged in a form of a horizontal U and having substantially all of the surface on both sides of said wall exposed to the circulating air within said provision compartment, the space between said walls being open at the top and bottom thereof adjacent said walls.

2. Evaporator construction including a U- shaped evaporator element, said element comprising vertical Walls and including a lower liquid distributing header and an upper header interconnected by refrigerant passages, the space between said walls being open at the top and bottom thereof adjacent said walls, means for supplying liquid refrigerant to said evaporator comprising a branch liquid line having a part connected to each end of said liquid header, and means for conducting vaporous refrigerant from said evaporator comprising a suction conduit connected with said upper header,

3. Refrigerating apparatus including an evaporator having a plurality of sections arranged so as to be supplied with liquid refrigerant in series, one of said sections comprising a vertical wall having a refrigerant passageway thermally associated therewith, and the other of said sections comprising a horizontal wall having a refrigerant passage thermally associated therewith, said vertical wall arranged in the shape of 4a U being open at the top and bottom, the periphery of said -horizontal w-all being spaced inwardly of said vertical Wall so as to permit -air to circulate over both sides of said 'vertical Wall 'throng-hout the entire extent thereof.

4. In an evaporator construction f'or 'a refrigerator including a plurality of evaporator sections connected in series, one of said sect-ions being adapted to produce refrigeration at Va rst temperature and the other of said evaporator sections being adapted to produce refrigeration at another temperature, one of said sections comprising a vertically arranged wall -formed with refrigerant passages therein, therother of lation of air on both sides of said vertical wall,

a sleeve embracing said horizontal wall portion forshielding theY s amehfrom said circulating air, and means for delivering refrigerant to a irst one of said sections and for withdrawing vaporous refrigerant from the other one of said sections.

SAMUEL E. BICKLE. 

